D.gnu - gdmd -man fails perhaps due to out-of-date commands?

Calling gdmd -man is supposed to open the default browser and load the user
documentation. However, on my system (Ubuntu 13.04, Unity interface) the
command fails with the errors:
Use of uninitialized value $ENV{"KDE_FULL_SESSION"} in string eq at
/opt/gdc/bin/gdmd line 289.
Can't exec "gnome-open": No such file or directory at /opt/gdc/bin/gdmd line
297.
I'm not familiar with perl so can't readily debug, but it obviously relates to
the following function:
sub browse($) {
my ($url) = _;
my cmd;
if ($^O =~ m/MSWin32/i) {
cmd = qw(cmd /c start);
} elsif ($^O =~ m/darwin/i &&
-x '/usr/bin/open') { # MacOS X vs. just Darwin
cmd = 'open';
} elsif ($ENV{KDE_FULL_SESSION} eq 'true') {
cmd = qw(kfmclient exec);
} elsif ($ENV{GNOME_DESKTOP_SESSION_ID} ne '') {
cmd = 'gnome-open';
} else {
errorExit "Sorry, I do not know how to start your browser.\nManual URL:
$url"
}
push cmd, $url;
system cmd;
print "Opening documentation page.";
exit 0;
}
... and looks likely to be down to out-of-date or buggy calls to environment
variables. The closest I was able to find searching online were these issues in
xgamer:
https://code.google.com/p/xgamer/issues/detail?id=8https://code.google.com/p/xgamer/issues/detail?id=9
... but it's not obvious what the fix referred to was.
There's no gnome-open on my system (or available in repos) so I presume this is
an old GNOME 2 command that's been removed?
In any case, this looks like something that needs to be addressed for a number
of other reasons, e.g. it appears to assume 32-bit Windows. The simplest thing
to do might be to simply delete the -man option.